Intraocular lenses (IOLs) are implanted in patients' eyes either to replace a patient's lens or, in the case of a phakic IOL, to complement the patient's lens. Some conventional IOLs are single focal length IOLs, while others are multifocal IOLs. Single focal length IOLs have a single focal length or single power. Objects at the focal length from the eye/IOL are in focus, while objects nearer or further away may be out of focus. Multifocal IOLs, on the other hand, have at least two focal lengths. Multifocal lenses may assist patients having conditions such as near-sightedness. In general, a physician selects an IOL having the appropriate base power and other characteristics for the patient. During ophthalmic surgery, often performed for other conditions such as cataracts, the selected IOL is implanted.
Although the IOLs function acceptably well in most patients, the selected IOL may have incorrect power for the patient. The IOL can be removed and a new IOL selected and implanted. However, performing additional ophthalmic surgeries for this purpose is undesirable. Other IOLs may have their power adjusted noninvasively. For example, the IOL may be sensitive to ultraviolet (UV) light. Such an IOL may be exposed to UV light in order to change the power of the lens. The exposure to UV light may change the shape of the IOL and, therefore, the base power of the lens. Although this method allows the base power of the IOL to be adjusted, such an IOL requires the patient to wear UV light blocking glasses at all times until an adjustment phase is completed. The adjustment phase is typically on the order of two weeks. Requiring a patient to wear UV light blocking glasses twenty-four hours per day for two weeks is inconvenient for the patient and undesirable. Once the adjustment phase is completed, the changes to the IOL must be locked in to prevent further changes to the IOL power due to every day exposure to UV light. Once these changes are locked in, no further adjustments may be made to the base power of the IOL. Other mechanisms, such as a change in tension, exist to change the base power of the lens. However, these mechanisms have attendant issues shortcomings.
Accordingly, what is needed is an improved mechanism for noninvasively changing the base power of an IOL.